Occupation and the risk of laryngeal cancer in Uruguay

Our plain-English summary of Occupation and the risk of laryngeal cancer in Uruguay, by E. De Stefani, P. Boffetta, F. Oreggia, et al (American Journal of Industrial Medicine, 1998).

The study

• Authors: E. De Stefani, P. Boffetta, F. Oreggia, A. Ronco, M. Kogevinas, M. Mendilaharsu
• Journal: American Journal of Industrial Medicine
• Published: 1998;33(6):537-42
• Cited by: 38 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In a case-control analysis involving 112 patients afflicted by laryngeal cancer and 509 controls diagnosed with cancers not related to tobacco and alcohol exposures, we studied the effects of type of employment and of substances present in the workplace on laryngeal cancer risk. Effects were measured relative to those never employed or never exposed to the substances. All analyses were controlled for age, tobacco smoking, and alcohol drinking through unconditional logistic regression and stratified analysis. Among job titles, butchers, vintners, bakers, and car assemblers presented elevated risks of laryngeal cancer (OR for butchers 2.8, 95% CL 1.1-7.2). Similarly, asbestos, mists from strong inorganic acids and pesticide exposures were associated with increased risks of laryngeal cancer (OR for strong acids 1.8, 95% 1.1-2.9).

In plain English

This case-control study looked at jobs and workplace substances in relation to laryngeal cancer (cancer of the voice box) in Montevideo, Uruguay. It compared 112 men aged 30 to 75 with laryngeal cancer, admitted to five major hospitals between 1993 and 1995, with 509 men who had other cancers not linked to tobacco or alcohol. Asbestos exposure was assessed through interview questions about tasks such as handling Eternit asbestos sheets, insulation work, and brakes, clutches or gaskets. Fiber types were not reported. Results were adjusted for smoking, drinking, age and other factors. Men ever exposed to asbestos had an odds ratio of 1.8 (95% limits 0.9 to 3.2), which was not statistically significant. Men exposed for 20 or more years had an odds ratio of 2.4 (1.2 to 4.8), and risk rose significantly with duration of exposure. Results were similar when colorectal cancer patients were dropped from the comparison group. Butchers, long-term exposure to strong acid mists, and fungicide exposure also showed raised risks. The authors cited a small case series, multiple comparisons and crude exposure assessment as limitations. They concluded that the asbestos finding replicated earlier studies.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Hospital-based case-control study, with controls drawn from patients with other cancers; part of a larger multi-site case-control study of occupational cancer in Uruguay
• Who was studied: Men aged 30 to 75 admitted to five major hospitals in Montevideo, Uruguay, January 1993 to December 1995. There were 112 laryngeal cancer cases (all squamous cell carcinomas) and 509 controls with other cancers. Controls excluded oral, pharyngeal, esophageal, gastric, bladder and lung cancer.
• Exposure: Self-reported occupational asbestos exposure, assessed by probing questions about tasks: Eternit asbestos sheets used in construction, insulation work, brakes, clutches and/or gaskets, asbestos mesh used for heating, and furnaces. No fiber type was specified. Other job titles and substances (including strong inorganic acid mists and pesticides) were also studied.
• Main results:
  • Ever exposed to asbestos: 23 cases and 70 controls, odds ratio 1.8 (95% CL 0.9 to 3.2), not statistically significant
  • Asbestos exposure of 20 or more years: odds ratio 2.4 (95% CL 1.2 to 4.8)
  • Asbestos exposure of 20 or more years: the article's own odds ratio and confidence limits
  • Laryngeal cancer risk increased significantly with duration of asbestos exposure
  • Asbestos results remained similar after colorectal cancer patients were excluded from the controls (data not shown)
  • Asbestos by tumor subsite: supraglottic odds ratio 2.3 (0.9 to 5.7); glottic odds ratio 2.9 (0.8 to 10.5)
  • Black tobacco smokers ever exposed to asbestos: odds ratio 3.9 (95% CL 1.7 to 9.5), compared with blond tobacco smokers not exposed to asbestos (data not shown)
  • Butchers: odds ratio 2.8 (95% CL 1.1 to 7.2) for those ever employed as butchers
  • Strong inorganic acid mists, 20 or more years of exposure: odds ratio 1.8 (95% CL 1.1 to 3.1)
  • Fungicides, 20 or more years of exposure: odds ratio 3.7 (95% CL 1.3 to 10.7)
• The authors' conclusion: The authors concluded that the study replicated previous findings on asbestos and strong inorganic acid exposures. They wrote that it presented new associations with working as a butcher and with pesticide exposure, which should be explored further.
• Limitations the authors state:
  • The case series was small
  • Multiple comparisons could have produced chance findings
  • Exposure assessment was crude, and the self-reported probing questions could lead to nondifferential misclassification

Topics

The National Library of Medicine indexes this study under subjects our site covers: Throat and laryngeal cancer.

Medical terms in this study, explained in our Lexicon: Laryngeal Cancer.

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• Occupational risk factors for laryngeal carcinoma: Connecticut, 1975-1980 — R.T. Zagraniski, J.L. Kelsey, et al. (1986)
• The joint effect of asbestos exposure, tobacco smoking and alcohol drinking on laryngeal cancer risk: evidence from the French population-based case-control study, ICARE — G. Menvielle, A. Fayossé, et al. (2016)
• A case-control study of occupational risk factors for laryngeal cancer — P. Wortley, T.L. Vaughan, et al. (1992)
• Diet and other risk factors for laryngeal cancer in Shanghai, China — W. Zheng, W.J. Blot, et al. (1992)

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